When using the keyboard shortcut Win + arrow key to position an active window to various positions on the screen (e.g, top left, right side, full screen, etc.), Windows 10 will display other active windows next to it. To stop this behavior, navigate to Settings -> System -> Multitasking and turn off “When I snap a window, show what I can snap next to it”. Next time you use this keyboard shortcut to position an active window it will immediately go where you want without showing any other active windows.